Position detector, position detecting method and analyzer

ABSTRACT

A position detector is for detecting a position of liquid held in a vessel. The position detector includes a sound wave generator disposed in contact with the vessel and having a plurality of sound generating elements for generating a sound wave by electrical energy; and a measuring unit that measures electrical characteristics of each of the sound generating elements based on the electrical energy reflected from each of the sound generating elements. The position detector also includes a determining unit that determines the presence or absence of the liquid at a position of each of the sound generating elements based on difference in the electrical characteristics measured at the measuring unit.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of PCT international application Ser.No. PCT/JP2006/324079 filed Dec. 1, 2006 which designates the UnitedStates, incorporated herein by reference, and which claims the benefitof priority from Japanese Patent Application. Nos. 2006-023818,2006-023819, and 2006-023820, all filed Jan. 31, 2006, the entirecontents of all of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a position detector, a positiondetecting method and an analyzer for detecting a position of liquid heldin a vessel.

2. Description of the Related Art

Conventionally, the analyzer analyzes constituent concentration or thelike of a specimen by measuring optical characteristics of the liquidheld in a reaction vessel (for example, see Japanese Patent ApplicationLaid-Open No. 2002-116213).

In the analyzer, when a capacity of the reaction vessel to be usedbecomes as small as a few nanoliters (nL) to several tens of microliters(μL), an opening through which liquid such as a reagent and a specimenis dispensed becomes relatively narrow relative to the reaction vesseldue to downsizing and an effect of surface tension of the liquid becomesextremely large. Therefore, when using the downsized reaction vessel,there has been a case in which in the reaction vessel, the liquid suchas the reagent and the specimen is held in the vicinity of the openingand is not introduced to the bottom portion thereof, thus making itimpossible to know at which position of the reaction vessel the liquidexists.

SUMMARY OF THE INVENTION

A position detector according to one aspect of the present invention isfor detecting a position of liquid held in a vessel. The positiondetector includes a sound wave generator disposed in contact with thevessel and having a plurality of sound generating elements forgenerating a sound wave by electrical energy; a measuring unit thatmeasures electrical characteristics of each of the sound generatingelements based on the electrical energy reflected from each of the soundgenerating elements; and a determining unit that determines the presenceor absence of the liquid at a position of each of the sound generatingelements based on difference in the electrical characteristics measuredat the measuring unit.

A position detecting method according to another aspect of the presentinvention is for detecting a position of liquid held in a vessel. Themethod includes individually generating a sound wave from each of aplurality of sound generating elements provided on the vessel byelectrical energy; measuring electrical characteristics of each of thesound generating elements based on the electrical energy reflected fromeach of the sound generating elements; and determining a presence orabsence of the liquid at a position of each of the sound generatingelements based on difference in the measured electrical characteristicsto detect a position of the liquid held in the vessel based on thedetermination of presence or absence of the liquid.

A position detector according to still another aspect of the presentinvention is for detecting a position of liquid held in a vessel. Theposition detector includes a plurality of light sources disposed so asto approach the vessel, each light source emitting measurement light formeasuring optical characteristics of the liquid; a plurality of lightreceivers disposed to face the plurality of light sources, respectively,each light receiver receiving the measurement light penetrating thevessel; and a detector that detects a position of the liquid held in thevessel based on photometric data in the light receivers.

An analyzer according to still another aspect of the present inventionis for stirring different liquids to react and measuring opticalcharacteristics of reaction liquid to analyze the reaction liquid. Theanalyzer includes a position detector according to the presentinvention.

An analyzer according to still another aspect of the present inventionis for measuring optical characteristics of liquid. The analyzerincludes a vessel for holding the liquid in a state of having at leasttwo gas-liquid interfaces; and a photometric unit that measures theoptical characteristics of the liquid held in the vessel.

A vessel according to still another aspect of the present invention isused in an analyzer for measuring optical characteristics of liquid. Thevessel includes an opening for introducing the liquid; and a liquidholding section for holding the liquid introduced from the opening in astate of having at least two gas-liquid interfaces.

An analyzer according to still another aspect of the present inventionis for measuring optical characteristics of liquid held in a vessel. Theanalyzer includes a photometric unit that measures the opticalcharacteristics of the liquid; and a control unit that controls aphotometric position at which the photometric unit performs photometryof the liquid based on a position at which the liquid is held in thevessel.

A photometric method of an analyzer according to still another aspect ofthe present invention is for measuring optical characteristics of liquidheld in a vessel. The method includes controlling a photometric positionat which photometry of the liquid is performed based on a position atwhich the liquid is held in the vessel; and performing the photometry ofthe liquid at the controlled photometric position.

The above and other objects, features, advantages and technical andindustrial significance of this invention will be better understood byreading the following detailed description of presently preferredembodiments of the invention, when considered in connection with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic configuration diagram showing an automaticanalyzer of a first embodiment;

FIG. 2 is a perspective view showing a reaction vessel used in theautomatic analyzer of the first embodiment together with a schematicconfiguration diagram of a part of a reaction wheel and a stirrer;

FIG. 3 is a vertical cross-sectional view of the reaction vesselillustrating a relationship among surface tension of held liquid, forceacting vertically upward from internal air and gravity of the liquid inthe reaction vessel used in the automatic analyzer of the firstembodiment;

FIG. 4 is a plan view of the reaction vessel of FIG. 3;

FIG. 5 is a cross-sectional view showing dispensing of a reagent to thereaction vessel by a reagent dispensing mechanism;

FIG. 6 is a cross-sectional view showing dispensing of a specimen to thereaction vessel of FIG. 5 by a specimen dispensing mechanism;

FIG. 7 is a cross-sectional view of the reaction vessel showing a statein which a liquid specimen obtained by mixing the reagent and thespecimen is stirred by a sound wave generated by a transducer of asurface acoustic wave device;

FIG. 8 is a cross-sectional view of the reaction vessel showing a statein which photometry of reaction liquid of the reagent and the specimenis performed by a bundle of light emitted from a light source at aninitial position of a photometry unit;

FIG. 9 is a cross-sectional view of the reaction vessel showing a statein which the reaction liquid after the photometry is sucked by a suckingnozzle of a cleaner from the reaction vessel after the photometry;

FIG. 10 is a cross-sectional view of the reaction vessel showing a statein which a cleaning liquid is dispensed to the reaction vessel fromwhich the reaction liquid has been sucked;

FIG. 11 is a cross-sectional view of the reaction vessel showing a statein which the dispensed cleaning liquid is stirred by the sound wavegenerated by the transducer of the surface acoustic wave device to cleanthe reaction vessel;

FIG. 12 is a cross-sectional view of the reaction vessel showing a statein which the cleaning liquid, which has cleaned the reaction vessel, issucked by the sucking nozzle of the cleaner;

FIG. 13 is a cross-sectional view of the reaction vessel illustratingstirring of the liquid specimen and control of the photometric positionin a case in which an amount of the liquid specimen is large;

FIG. 14 is a cross-sectional view of the reaction vessel illustratingstirring of the liquid specimen and control of the photometric positionin a case in which a holding position of the liquid specimen isdifferent;

FIG. 15 is an enlarged view of a portion A of FIG. 14;

FIG. 16 is a cross-sectional view of the reaction vessel illustratingstirring of the liquid specimen and control of the photometric positionin a case in which an arrangement of the reaction vessel is different;

FIG. 17 is a perspective view showing a first modified example of thereaction vessel;

FIG. 18 is a cross-sectional view of the reaction vessel shown in FIG.17;

FIG. 19 is a cross-sectional view showing a second modified example ofthe reaction vessel;

FIG. 20 is a front view showing a modified example of the surfaceacoustic wave device;

FIG. 21 is a frequency characteristic diagram of impedance and phase ofthe surface acoustic wave device shown in FIG. 20;

FIG. 22 is a view showing a first drive example of the surface acousticwave device shown in FIG. 20;

FIG. 23 is a cross-sectional view of the reaction vessel showing a statein which the sound wave generated by the transducer of the surfaceacoustic wave device driven in the first drive example leaks into theliquid held in the vicinity of the opening of the liquid holdingsection;

FIG. 24 is a view showing a second drive example of the surface acousticwave device shown in FIG. 20;

FIG. 25 is a cross-sectional view of the reaction vessel showing a statein which the sound wave generated by the transducer of the surfaceacoustic wave device driven in the second drive example leaks into theliquid held in the vicinity of the opening of the liquid holdingsection;

FIG. 26 is a cross-sectional view of a concave portion of a reactionwheel showing a modified example to supply the electrical power to thesurface acoustic wave device by a contact together with a schematicconfiguration diagram of a stirrer;

FIG. 27 is a front view of the surface acoustic wave device used in themodified example shown in FIG. 26;

FIG. 28 is a perspective view showing the automatic analyzer of a secondembodiment together with a schematic configuration diagram of thereaction vessel, a part of the reaction wheel and the stirrer;

FIG. 29 is a front view showing the surface acoustic wave device used inthe reaction vessel shown in FIG. 28 and used in position detection ofthe liquid held in the reaction vessel;

FIG. 30 is a time variation diagram of frequency showing an example ofdrive with time of the surface acoustic wave device shown in FIG. 29;

FIG. 31 is a cross-sectional view showing a case in which the liquidholding section of the reaction vessel to which the surface acousticwave device shown in FIG. 29 is attached is empty;

FIG. 32 is a frequency characteristic diagram regarding reflectivity ofa drive signal in a case in which the surface acoustic wave device shownin FIG. 31 is driven;

FIG. 33 is a cross-sectional view showing a case in which the liquid isheld in the vicinity of the opening on an upper portion of the liquidholding section of the reaction vessel shown in FIG. 29;

FIG. 34 is a frequency characteristic diagram regarding reflectivity ofa drive signal in a case in which the surface acoustic wave device shownin FIG. 33 is driven;

FIG. 35 is a cross-sectional view showing a case in which the liquid isheld from the vicinity of the opening of the reaction vessel shown inFIG. 29 to near the lower portion of the liquid holding section;

FIG. 36 is a frequency characteristic diagram regarding reflectivity ofa drive signal in a case in which the surface acoustic wave device shownin FIG. 35 is driven;

FIG. 37 is a cross-sectional view showing a case in which the liquidintrudes into the bottom portion of the reaction vessel shown in FIG.29;

FIG. 38 is a frequency characteristic diagram regarding reflectivity ofa drive signal in a case in which the surface acoustic wave device shownin FIG. 37 is driven;

FIG. 39 is a block diagram showing a configuration of the automaticanalyzer of a third embodiment by showing a cross-section of thereaction vessel and the reaction table;

FIG. 40 is a plan view showing a part of the reaction table used in theautomatic analyzer in FIG. 39 together with the surface acoustic wavedevice and the driver thereof;

FIG. 41 is a perspective view showing an arrangement of a holder, thereaction vessel and the surface acoustic wave device on the reactiontable forming the automatic analyzer in FIG. 39;

FIG. 42 is a cross-sectional view showing an arrangement of a holder,the reaction vessel and the surface acoustic wave device on the reactiontable forming the automatic analyzer in FIG. 39 and acoustic matchingliquid dropped on the surface acoustic wave device;

FIG. 43 is a cross-sectional view corresponding to FIG. 42 showing astate in which the surface acoustic wave device abuts a side wall of thereaction vessel though an abutting window formed in the holder;

FIG. 44 is a cross-sectional view corresponding to FIG. 42 showing amodified example of the holder;

FIG. 45 is a block diagram schematically showing a configuration of theautomatic analyzer of a fourth embodiment together with a cross-sectionof the reaction vessel;

FIG. 46 is a block diagram corresponding to FIG. 45 showing a case inwhich an amount of the liquid held in the reaction vessel is large;

FIG. 47 is a block diagram schematically showing the configuration ofthe automatic analyzer of a fifth embodiment together with thecross-section of the reaction vessel;

FIG. 48 is a block diagram corresponding to FIG. 47 showing a case inwhich an amount of the liquid held in the reaction vessel is large;

FIG. 49 is a block diagram schematically showing the configuration ofthe automatic analyzer of a sixth embodiment together with thecross-section of the reaction vessel;

FIG. 50 is a block diagram schematically showing a first modifiedexample of the automatic analyzer of the sixth embodiment together withthe cross-section of the reaction vessel; and

FIG. 51 is a block diagram schematically showing a second modifiedexample of the automatic analyzer of the sixth embodiment together withthe cross-section of the reaction vessel.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, a first embodiment of an analyzer of the present inventionwill be described in detail with reference to the drawings. FIG. 1 is aschematic configuration diagram showing an automatic analyzer of thefirst embodiment. FIG. 2 is a perspective view showing a reaction vesseltogether with a schematic configuration diagram of a part of a reactionwheel and a stirrer. FIG. 3 is a longitudinal sectional view of thereaction vessel illustrating a relationship among surface tension ofheld liquid, force acting vertically upward from internal air andgravity of the liquid, in the reaction vessel. FIG. 4 is a plan view ofthe reaction vessel of FIG. 3.

An automatic analyzer 1 is provided with a specimen table 3, a specimendispensing mechanism 5, a reaction wheel 6, a photometry unit 10, acleaner 11, a reagent dispensing mechanism 12 and a reagent table 13 ona working table 2, as shown in FIG. 1, and is also provided with astirrer 20.

The specimen table 3 is rotated in a direction indicated by an arrow bydrive means and a plurality of storage chambers 3 a arranged at regularintervals along a circumferential direction are provided on an outercircumference thereof, as shown in FIG. 1. A specimen vessel 4 in whichthe specimen is accommodated is detachably stored in each storagechamber 3 a.

The specimen dispensing mechanism 5 is means for dispensing the specimento a plurality of reaction vessels 7 held on the reaction wheel 6, andas shown in FIG. 1, sequentially dispenses the specimen from a pluralityof specimen vessels 4 on the specimen table 3 to the reaction vessels 7.The specimen dispensing mechanism 5 outputs a dispensing amount of thespecimen dispensed to the reaction vessels 7 to a control unit 16.

The reaction wheel 6 is rotated in a direction indicated by an arrow bydrive means different from that of the specimen table 3 and a pluralityof concave portions 6 a are provided at regular intervals along acircumferential direction on an outer circumference thereof, as shown inFIG. 1. On the reaction wheel 6, slits 6 b (see FIG. 2) through whichmeasurement light passes are formed on both sides in a radial directionof each concave portion 6 a. The slit 6 b is shaped to have a lengthsubstantially corresponding to a vertical direction of a liquid holdingsection 7 d of the reaction vessel 7. The reaction wheel 6 rotatesclockwise by (one revolution minus one reaction vessel)/4 per one cycle,and rotates counterclockwise by one concave portion 6 a per four cycles.The photometry unit 10 and the cleaner 11 are provided in the vicinityof the reaction wheel 6.

The reaction vessel 7 has a capacity as small as a few nanoliters (nL)to several tens of microliters (μL), and a transparent material, whichtransmits not less than 80% of light included in analytical light (340to 800 nm) emitted from a light source 10 a of the photometry unit 10,for example, glass including heat-resistant glass and synthetic resinsuch as cyclic olefin and polystyrene are used. The reaction vessel 7 isa square tubular cuvette in which the liquid holding section 7 d havinga square horizontal cross section for holding the liquid is formed ofside walls 7 a and 7 b and a bottom wall 7 c and having an opening 7 eon an upper portion of the liquid holding section 7 d, as shown in FIGS.2 and 4. In the reaction vessel 7, a treatment to impart affinity forliquid such as the specimen and a reagent is applied to an inner surfaceof the liquid holding section 7 d, and two side walls 7 a arranged so asto be opposed to each other to transmit the analytical light are usedfor optical measurement of the liquid. The reaction vessel 7 is arrangedin the concave portion 6 a such that the side walls 7 a are directed toa radial direction of the reaction wheel 6 and the side walls 7 b aredirected to a circumferential direction of the reaction wheel 6.

Herein, there is used the reaction vessel 7 having an angle of contactwith which when liquid Lq is held in a state of having at least twogas-liquid interfaces M1 and M2, as shown in FIGS. 3 and 4, a sum of avolume of a vertical component of surface tension T (F=T·cos θ·L) actingfrom the held liquid Lq to an entire circumference of an inner wall andforce (f=ΔP·S) acting vertically upward from gas, for example, air Ar inthe reaction vessel 7 on the liquid Lq, is not smaller than gravity(W=ρ·g·H·S) acting on the liquid Lq as represented by the followingequation:

F+f=(T·cos θ·L+ΔP·S)≧W=ρ·g·H·S.

At this time, as shown, the angle of contact between the reaction vessel7 and the held liquid Lq, a length along a circumferential direction inthe gas-liquid interface between the liquid Lq and the reaction vessel7, atmosphere pressure acting on the gas-liquid interface M1, pressureacting from the air Ar in the reaction vessel 7 on the gas-liquidinterface M2, density of the liquid Lq, gravity acceleration, a lengthin a vertical direction of the liquid Lq held in the reaction vessel 7and a cross-sectional area in a horizontal direction of the liquidholding section 7 d are set to θ, L, P1, P2 (ΔP=P1−P2), ρ, g, H and S,respectively. If the reaction vessel 7 has such an angle of contact θwith respect to the liquid Lq, a sum of the surface tension and thepressure of the air Ar is not smaller than the gravity, so that theliquid Lq is held at the opening 7 e. Such relationship among thesurface tension F, the force f acting on the liquid Lq and the gravity Win the reaction vessel 7 is similarly applied also to another reactionvessel used in each embodiment to be described later, when the air Arexists in the reaction vessel 7.

The photometry unit 10 is photometric means provided on positionsopposed to each other in the radial direction with the concave portion 6a on a lower portion of the reaction wheel 6 interposed therebetween soas to be movable up and down, and has the light source 10 a for emittingthe analytical light (340 to 800 nm) for analyzing the liquid held inthe reaction vessel 7 and a light receiver 10 b for dispersing theanalytical light, which has penetrated the liquid and receiving thesame. A vertical position (photometric position) of the photometry unit10 is controlled such that the light source 10 a and the light receiver10 b move in the vertical direction, which intersects with thegas-liquid interface of the liquid held in the reaction vessel 7, bymeans of a driver Dr such as a z-axis stage of which operation iscontrolled by the control unit 16.

The cleaner 11 has discharge means for discharging the liquid andcleaning liquid from the reaction vessel 7 and dispensing means for thecleaning liquid. The cleaner 11 discharges the liquid after photometryfrom the reaction vessel 7 after the photometry and after that,dispenses the cleaning liquid. A dispensing amount of the cleaningliquid is set to be slightly larger than that of the liquid held in thereaction vessel 7 at the time of the photometry. The cleaner 11 cleansthe inside of the reaction vessel 7 by repeating a plurality of timesoperations of dispensing and discharging the cleaning liquid. Thereaction vessel 7 thus cleaned is used again for analyzing a newspecimen.

The reagent dispensing mechanism 12 is means for dispensing the reagentto a plurality of reaction vessels 7 held on the reaction wheel 6, andsequentially dispenses the reagent from a predetermined reagent vessel14 on the reagent table 13, to the reaction vessel 7 as shown in FIG. 1.The reagent dispensing mechanism 12 outputs the dispensing amount of thereagent dispensed to the reaction vessel 7 to the control unit 16 as adispensing amount signal.

The reagent table 13 is rotated in a direction indicated by an arrow bydrive means different from that of the specimen table 3 and of thereaction wheel 6, and a plurality of storage chambers 13 a shaped into afan are provided along the circumferential direction thereof, as shownin FIG. 1. The reagent vessel 14 is detachably stored in each storagechamber 13 a. Each of a plurality of reagent vessels 14 is filled with apredetermined reagent according to an inspection item, and a barcodelabel (not shown) indicating information regarding the accommodatedreagent is adhered to an outer surface thereof.

Herein, a reader 15 for reading information such as a kind, a lot, andan expiration date of the reagent recorded on the barcode label adheredto the reaction vessel 14, and outputting the information to the controlunit 16 is provided on an outer circumference of the reagent table 13,as shown in FIG. 1.

The control unit 16 is connected to the specimen table 3, the specimendispensing mechanism 5, the reaction wheel 6, the light receiver 10 b,the cleaner 11, the reagent dispensing mechanism 12, the reagent table13, the reader 15, an analysis unit 17, an input unit 18, a display unit19 and the stirrer 20, and a microcomputer or the like provided with astoring function for storing an analytical result is used, for example.The control unit 16 controls an operation of each section of theautomatic analyzer 1, and based on the information read from the recordof the barcode label, if the lot, the expiration date and the like ofthe reagent are out of a set range, controls the automatic analyzer 1 tostop an analytical operation or alerts an operator.

Also, the control unit 16 obtains in advance a table and a function fordeciding the vertical position, that is, the photometric position of thephotometry unit 10, based on the dispensing amounts of the specimen andthe reagent input from the specimen dispensing mechanism 5 and thereagent dispensing mechanism 12, respectively, and controls operation ofthe driver Dr driving the photometry unit 10 based on the table and thefunction, thereby controlling the photometric position. Herein, when ameasurement item of the specimen and position information of thereaction vessel 7 are input from the input unit 18, signalscorresponding to the input measurement item and the position informationof the reaction vessel 7 are output to the control unit 16. The controlunit 16 allows the specimen dispensing mechanism 5 and the reagentdispensing mechanism 12 to dispense the specimen and the reagent in apredetermined amount to a specified reaction vessel 7 based on thesignals. At this time, as described above, the specimen dispensingmechanism 5 and the reagent dispensing mechanism 12 output thedispensing amount signals regarding the dispensing amounts of thespecimen and the reagent dispensed to the reaction vessel 7 to thecontrol unit 16. The control unit 16 outputs the dispensing amountsignal to the stirrer 20, and reads the photometric position measuredand stored in advance regarding the reaction vessel 7 based on thedispensing amount signal input in this manner, thereby controlling thephotometric position of the photometry unit 10 by means of the driverDr.

The analysis unit 17 is connected to the light receiver 10 b through thecontrol unit 16, analyzes a constituent concentration or the like of thespecimen from light absorbance of the liquid in the reaction vessel 7based on an amount of light received by the light receiver 10 b, andoutputs the analytical result to the control unit 16. The input unit 18is the section to perform operation of inputting the inspection item orthe like to the control unit 16, and a keyboard, a mouse and the likeare used, for example. The display unit 19 is for displaying analyticalcontents and the alert, and a display panel or the like is used.

The stirrer 20 is for driving a surface acoustic wave device 22, and hasan electrical power transmitter 21 for transmitting an electrical powerto the surface acoustic wave device 22 and the surface acoustic wavedevice 22, as shown in FIG. 2.

The electrical power transmitter 21 has an RF transmission antenna 21 a,a drive circuit 21 b and a controller 21 c. The electrical powertransmitter 21 transmits the electrical power supplied from ahigh-frequency alternating-current source of about a few MHz to severalhundreds of MHz from the RF transmission antenna 21 a to the surfaceacoustic wave device 22 as the drive signal. The RF transmission antenna21 a is attached to an inner surface of the concave portion 6 a of thereaction wheel 6. Therefore, the stirrer 20 switches to output thesupplied electrical power to a specific RF transmission antenna 21 a outof a plurality of RF transmission antennas 21 a by turning a switchcontrolled by the controller 21 c, for example.

The drive circuit 21 b has an oscillation circuit capable of changing anoscillation frequency based on a control signal from the controller 21 cand outputs a high-frequency oscillation signal of about several tens ofMHz to several hundreds of MHz to the RF transmission antenna 21 a.Herein, the RF transmission antenna 21 a and the drive circuit 21 b areconnected through a contact electrode such that the electrical power istransmitted even when the reaction wheel 6 rotates. The controller 21 ccontrols operation of the drive circuit 21 b, and controls, for example,characteristics (frequency, intensity, phase, characteristics of wave),waveforms (sine wave, triangle wave, rectangular wave, burst wave, orthe like) or modulations (amplitude modulation, frequency modulation) orthe like of a sound wave generated by the surface acoustic wave device22. Also, the controller 21 c may switch the frequency of theoscillation signal oscillated by the drive circuit 21 b according to anincorporated timer.

The surface acoustic wave device 22 is stirring means, which receivesthe drive signal (electrical power) transmitted from the RF transmissionantenna 21 a to generate the sound wave (surface acoustic wave), therebystirring the liquid by the generated sound wave. The surface acousticwave device 22 is attached to the side wall 7 a of the reaction vessel 7through an acoustic matching layer of epoxy resin or the like, as shownin FIG. 2. In the surface acoustic wave device 22, a transducer 22 bformed of an interdigital transducer (IDT) and an antenna 22 c areformed on a piezoelectric substrate 22 a formed of lithium niobate(LiNbO₃) or the like. The transducer 22 b is a sound generating elementfor generating the sound wave (surface acoustic wave) by receiving thedrive signal (electrical power) transmitted from the RF transmissionantenna 21 a by the antenna 22 c. The surface acoustic wave device 22avoids the side walls 7 a through which the analytical light emittedfrom the light source 10 a of the photometry unit 10 enters or emits andis attached to the side wall 7 b adjacent thereto.

The automatic analyzer 1 configured in this manner analyzes the specimendispensed to the reaction vessel 7 by a photometric method to bedescribed below including a process to control the photometric positionat which the photometry of the liquid is performed according to aholding position at which the liquid is held in the reaction vessel 7,and a process to perform the photometry of the liquid at the controlledphotometric position.

First, in the automatic analyzer 1 under the control of the control unit16, a dispensing nozzle 12 a of the reagent dispensing mechanism 12sequentially dispenses a reagent R from a predetermined reagent vessel14 of the reagent table 13 to the reaction vessel 7, which comes alongthe circumferential direction by the rotation of the reaction wheel 6(see FIG. 5). At this time, the reagent dispensing mechanism 12 outputsthe dispensing amount signal regarding the dispensing amount of thereagent dispensed to the reaction vessel 7 to the control unit 16.

Then, in the reaction vessel 7, since the capacity thereof is asextremely small as a few nanoliters (nL) to several tens of microliters(μL), the reagent R is held in the vicinity of the opening 7 e throughthe air Ar in a state of downwardly penetrating from the opening 7 e, asshown in FIG. 6, according to at least one of a kind or the amountthereof and a form or the material of the reaction vessel 7. That is,since the reaction vessel 7 has the angle of contact θ with which thesum of the volume of the vertical component of the surface tension T(F=T·cos θ·L) acting from the held reagent R on the entire circumferenceof the inner wall, and the force (f=ΔP·S) acting vertically upward fromthe air Ar on the reagent R is not smaller than the gravity (W=ρ·g·H·S)acting on the reagent R, the reagent R is held in the vicinity of theopening 7 e.

After dispensing the reagent R, the automatic analyzer 1 rotates thereaction wheel 6 under the control of the control unit 16 and moves thereaction vessel 7 to which the reagent R has been dispensed to thevicinity of the specimen dispensing mechanism 5. Next, the automaticanalyzer 1 drives the specimen dispensing mechanism 5 under the controlof the control unit 16. Thereby, in the reaction vessel 7, a specimen Sis dispensed from a predetermined specimen vessel 4 on the reagent R bya dispensing nozzle 5 a (see FIG. 6). Mixed liquid Lm of the reagent Rand the specimen S is held in the vicinity of the opening 7 e for theabove-described reason (see FIG. 7).

At this time, the specimen dispensing mechanism 5 outputs the dispensingamount signal regarding the dispensing amount of the specimen dispensedto the reaction vessel 7 to the control unit 16. Based on the dispensingamount signals regarding the dispensing amount of the reagent and thespecimen input in this manner, in the automatic analyzer 1, the controlunit 16 reads the photometric position stored in advance, and controlsthe photometric position of the photometry unit 10 by means of thedriver Dr. However, since the mixed liquid Lm of the reagent R and thespecimen S is held in the vicinity of the opening 7 e of the reactionvessel 7 as shown in FIG. 7, the control unit 16 holds the photometryunit 10 at an initial position thereof near the opening 7 e of thereaction vessel 7 and does not change the vertical position thereof.

After dispensing the reagent and the specimen to the reaction vessel 7in this manner, the automatic analyzer 1 drives the surface acousticwave device 22 by the driver 20 under the control of the control unit16. Thereby, in the reaction vessel 7, a sound wave Wa generated by thetransducer 22 b, which is the sound generating element, leaks to themixed liquid Lm as shown in FIG. 7, and the mixed liquid Lm is stirredby the leaked sound wave Wa. As a result, in the mixed liquid Lm, thereagent R and the specimen S react with each other.

The automatic analyzer 1 allows the reagent R and the specimen S toreact in this manner, thereby making reaction liquid Lr (see FIG. 8),and after that, moves the reaction vessel 7 holding the reaction liquidby rotating the reaction wheel 6 under the control of the control unit16. Thereby, in the reaction vessel 7, when this passes through thephotometry unit 10, the photometry of the reaction liquid Lr held in thevicinity of the opening 7 e is performed at the initial position of thephotometry unit 10 by a bundle of light EL emitted from the light source10 a, as shown in FIG. 8. Herein, a portion indicated by a broken linein FIG. 8 is a photometry area Rop. Meanwhile, as the bundle of lightshown in FIG. 8, the one having an oval shape at a cross sectionorthogonal to the moving direction is used.

After the photometry, the automatic analyzer 1 drives the cleaner 11under the control of the control unit 16, and sucks the reaction liquidLr after the photometry from the reaction vessel 7 after the photometryby a suction nozzle 11 a, as shown in FIG. 9. Next, the automaticanalyzer 1 discharges cleaning liquid Lc from a cleaning nozzle of thecleaner 11 to the reaction vessel 7, as shown in FIG. 10, under thecontrol of the control unit 16. An amount of the cleaning liquid Lc tobe discharged is set slightly larger than that of the reaction liquidLr, and this is discharged several times so as not to be accumulated atthe opening 7 e. In a case in which the cleaning liquid Lc accumulatesso as to block the opening 7 e, the surface acoustic wave device 22 isdriven and the cleaning liquid Lc is sent to the liquid holding section7 d by utilizing the generated sound wave for cleaning the liquidholding section 7 d.

Next, the automatic analyzer 1 drives the surface acoustic wave device22 by the driver 20 under the control of the control unit 16. Thereby,the reaction vessel 7 stirs the cleaning liquid Lc by the sound wave Waleaking into the cleaning liquid Lc, as shown in FIG. 11, as in the casein which the reagent R and the specimen S react with each other, andcleans the liquid holding section 7 d by the cleaning liquid Lc. Aftercleaning the reaction vessel 7, the automatic analyzer 1 drives thecleaner 11 under the control of the control unit 16, and sucks thecleaning liquid Lc, which has cleaned the liquid holding section 7 d, bythe suction nozzle 11 a, as shown in FIG. 12. The automatic analyzer 1cleans the reaction vessel 7 by allowing the cleaner 11 to repeat aplurality of times a series of operations of discharging, stirring andsucking of the cleaning liquid Lc under the control of the control unit16. The reaction vessel 7 cleaned in this manner is used again foranalyzing the new specimen.

In such a manner, when the capacity of the reaction vessel 7 becomes asextremely small as a few nanoliters (nL) to several tens of microliters(μL), the liquid is held in the vicinity of the opening 7 e due to alarge effect of the surface tension. Therefore, in a case in which theliquid is held in the vicinity of the opening 7 e, it is reasonable toperform the photometry in this state, since extra energy for sending theliquid to inside the reaction vessel 7 is not wasted.

However, the position at which the reaction vessel 7 holds the liquidincluding the reagent R and the specimen S varies according to at leastone of the kind or the amount of the liquid and the form or the materialof the reaction vessel 7. Therefore, for example, in a case in which thedispensing amounts of the reagent and the specimen are large and theamount of the mixed liquid Lm is large, as shown in FIG. 13, the controlunit 16 first drives the surface acoustic wave device 22 and stirs themixed liquid Lm by the sound wave Wa to allow the reagent R and thespecimen S to react with each other.

After that, the control unit 16 may perform the photometry of thereaction liquid at the initial position of the photometry unit 10without controlling the photometric position, or may perform thephotometry of the reaction liquid after controlling the photometricposition. In this case, the control unit 16 reads the photometricposition stored in advance based on the dispensing amount signalsregarding the dispensing amounts of the specimen and the reagent inputfrom the specimen dispensing mechanism 5 and the reagent dispensingmechanism 12, respectively, moves (lowers) the photometry unit 10 fromthe initial position thereof to a central portion in the verticaldirection of the reaction vessel 7 by means of the driver Dr, therebycontrolling the photometric position. Therefore, in the reaction vessel7, the photometry of the held reaction liquid is performed at thephotometric area Rop, which has moved downward.

On the other hand, there is a case in which the mixed liquid Lm intrudesinto the central portion in the vertical direction of the reactionvessel 7, and is held at the position distant from the transducer 22 bof the surface acoustic wave device 22, as shown in FIG. 14, even thoughthe amount thereof is small, for example, due to extremely small surfacetension or large density ρ. In such a case, the sound wave Wa generatedby the transducer 22 b is not radiated in the air of which acousticimpedance largely differs from that of the material of the reactionvessel 7. Therefore, the sound wave Wa is propagated through thepiezoelectric substrate 22 a and the side wall 7 b and is radiated inthe mixed liquid Lm at the portion of the mixed liquid Lm at which thedifference in acoustic impedance is small, as shown in FIG. 15. In thismanner, the mixed liquid Lm is stirred by an acoustic flow generated bythe sound wave Wa radiated in the mixed liquid Lm and the specimen andthe reagent react with each other, thereby the reaction liquid isobtained.

After that, the control unit 16 reads the photometric position stored inadvance based on the dispensing amount signals regarding the dispensingamounts of the specimen and the reagent input from the specimendispensing mechanism 5 and the reagent dispensing mechanism 12,respectively, lowers the photometry unit 10 from the initial positionthereof to central portion in the vertical direction of the reactionvessel 7 by means of the driver Dr, thereby controlling the photometricposition. Thereby, the automatic analyzer 1 may perform the photometryof the reaction liquid at the photometric area Rop (see FIG. 14) atwhich the reaction liquid of the reaction vessel 7 exists.

Also, since the capacity of the reaction vessel 7 is as small as a fewnanoliters (nL) to several tens, of microliters (μL), the effect of thesurface tension of the liquid is larger than that of the gravity actingon the held liquid. Therefore, the reaction vessel 7 may be arranged inthe concave portion 6 a of the reaction wheel 6 such that the opening 7e is directed vertically downward, as shown in FIG. 16. When thusconfigured, the control unit 16 reads the photometric position stored inadvance based on the dispensing amount signals regarding the dispensingamounts of the specimen and the reagent input from the specimendispensing mechanism 5 and the reagent dispensing mechanism 12,respectively, and lowers the photometry unit 10 from the initialposition thereof to the central portion in the vertical direction of thereaction vessel 7 by means of the driver Dr, thereby controlling thephotometric position. By controlling in such a manner, the automaticanalyzer 1 may perform the photometry of the reaction liquid Lr at thephotometric area Rop (see FIG. 16) at which the reaction liquid Lr ofthe reaction vessel 7 exists. Also, as another alternative embodiment,the reaction vessel 7 may be arranged in a horizontal direction. In thiscase, since the gas-liquid interfaces align in the horizontal direction,the photometric position of the photometry unit 10 is controlled betweenthe two gas-liquid interfaces. That is, the photometric position iscontrolled in the horizontal direction.

Herein, the reaction vessel has only to have the opening for introducingthe liquid and the liquid holding section for holding the liquid in astate of having at least two gas-liquid interfaces. Therefore, as areaction vessel 8 shown in FIGS. 17 and 18, the reaction vessel may beformed such that a liquid holding section 8 d for holding the liquid isformed of a pair of side walls 8 a arranged so as to face each other inparallel, a pair of inclined walls 8 b arranged so as to face each otherand become narrower in a downward direction and a bottom wall 8 c, andan opening 8 e is provided on an upper portion of the liquid holdingsection 8 d. At this time, the reaction vessel 8 is formed of the samematerial as that of the reaction vessel 7, the treatment to impartaffinity for liquid such as the specimen and the reagent is applied tothe inner surface thereof, and the capacity thereof is as small as thatof the reaction vessel 7. In the reaction vessel 8, the surface acousticwave device 22 is attached to the inclined walls 8 b and a pair of sidewalls 8 a is used for optically measuring the liquid. The reactionvessel 7 is arranged in the concave portion 6 a such that the side walls8 a are directed in the radial direction of the reaction wheel 6 and theinclined walls 8 b are directed in the circumference direction of thereaction wheel 6.

In the reaction vessel 8, the liquid dispensed from above is held in thevicinity of the opening 8 e by the effect of the surface tension as inthe reaction vessel 7. Therefore, the reaction vessel 8 stirs the mixedliquid Lm of the reagent R and the specimen S by the sound wave Wagenerated by the surface acoustic wave device 22 in the vicinity of theopening 8 e, as shown in FIG. 18, and the photometry of the reactionliquid is performed in the vicinity of the opening 8 e. However, theposition at which the reaction vessel 8 holds the liquid including thereagent R and the specimen S varies according to at least one of thekind or the amount of the liquid and the form or the material of thereaction vessel 8. Therefore, the control unit 16 may read thephotometric position stored in advance based on the dispensing amountsignals regarding the dispensing amounts of the specimen and the reagentinput from the specimen dispensing mechanism 5 and the reagentdispensing mechanism 12, respectively, and control the photometricposition of the photometry unit 10 by means of the driver Dr.

Also, the reaction vessel may form a liquid holding section 9 d havingopenings 9 c in upper and lower portions by two pairs of side walls 9 aarranged so as to face each other in parallel, as in the reaction vessel9 shown in FIG. 19. At this time, the reaction vessel 9 is formed of thesame material as that of the reaction vessel 7, the treatment to impartaffinity for liquid such as the specimen and the reagent is applied tothe inner surface thereof, and the capacity thereof is as small as thatof the reaction vessel 7.

Therefore, in the reaction vessel 9, the liquid dispensed from above isheld in the vicinity of the opening 9 c due to the effect of the surfacetension as in the reaction vessel 7. Therefore, the reaction vessel 9may stir the mixed liquid Lm of the reagent R and the specimen S by thesound wave Wa generated by the surface acoustic wave device 22 in thevicinity of the opening 9 c, as shown in FIG. 19, and perform thephotometry of the reaction liquid obtained by reacting the reagent R andthe specimen S in the vicinity of the opening 9 c. However, the positionat which the reaction vessel 9 holds the liquid including the reagent Rand the specimen S varies depending on at least one of the kind or theamount of the liquid and the form or the material of the reaction vessel9. Therefore, in such a case, the control unit 16 my read thephotometric position stored in advance based on the dispensing amountsignals regarding the dispensing amounts of the specimen and the reagentinput from the specimen dispensing mechanism 5 and the reagentdispensing mechanism 12, respectively, and control the photometricposition by the photometry unit 10 by means of the driver Dr.

On the other hand, the surface acoustic wave device may be configuredsuch that two transducers 24 b and 24 c each formed of the interdigitaltransducer (IDT) are formed on a piezoelectric substrate 24 a formed ofthe same material as that of the piezoelectric substrate 22 a and thetransducers 24 b and 24 c are parallelly connected by an antenna 24 d,as in the surface acoustic wave device 24 shown in FIG. 20. At thistime, the transducers 24 b and 24 c of which impedance and phaserelative to a drive frequency have frequency characteristics shown inFIG. 21 are used, and the center frequency of the transducer 24 blocated on an upper portion is set to f1 and the center frequency of thetransducer 24 c located on a lower portion is set to f2 (>f1). Also, thesurface acoustic wave device 24 is attached to the side wall 7 b of thereaction vessel 7 through an acoustic matching layer in a state in whichthe transducer 24 b is located on the upper portion.

Therefore, in the surface acoustic wave device 24, when the drive signalof the frequency f1 is transmitted from the RF transmission antenna 21 aof the electrical power transmitter 21, the transducer 24 b located onthe upper portion is excited, and when the drive signal of the frequencyf2 is transmitted, the transducer 24 c located on the lower portion isexcited.

Therefore, in the automatic analyzer 1, the stirrer 20 outputs the drivesignal of the frequency f1 from the controller 21 c to the surfaceacoustic wave device 24 under the control of the control unit 16, forexample, in a case in which the amount of the mixed liquid of thereagent and the specimen is small and this liquid is held in thevicinity of the opening 7 e on the upper side of the liquid holdingsection 7 d by the dispensing amount signals output from the controlunit 16 to the stirrer 20. Then, in the automatic analyzer 1, the drivesignal of the frequency f1 is transmitted from the RF transmissionantenna 21 a to the surface acoustic wave device 24 when the reactionwheel 6 stops.

Thereby, in the stirrer 20, the transducer 24 b located on the upperside of the surface acoustic wave device 24 is sequentially driven bythe drive signal of the frequency f during a stopping time Ts in whichthe reaction wheel 6 stops, as shown in FIG. 22. As a result, thesurface acoustic wave (sound wave) induced by the transducer 24 b whilethe reaction wheel 6 is stopped propagates within the side wall 7 b ofthe reaction vessel 7, and the sound wave Wa leaks into the mixed liquidLm of which acoustic impedance is closer, as shown in FIG. 23. Theacoustic flow is generated by the leaked sound wave Wa, and the reagent,and the specimen in the mixed liquid Lm are stirred. After stirring, thecontrol unit 16 performs the photometry of the reaction liquid at theinitial position (in the vicinity of the opening 7 e) of the photometryunit 10 without controlling the photometric position.

On the other hand, by the dispensing amount signals output from thecontrol unit 16 to the stirrer 20, for example, in a case in which theamount of the mixed liquid of the reagent and the specimen held in thevicinity of the opening 7 e of the liquid holding section 7 d is large,the stirrer 20 time-sharingly and alternately outputs the drive signalof the frequency f1 and the drive signal of the frequency f2 from thecontroller 21 c to the surface acoustic wave device 24 under the controlof the control unit 16. Then, in the automatic analyzer 1, when thereaction wheel 6 stops, the drive signal of the frequency f1 and thedrive signal of the frequency f2 are alternately transmitted from the RFtransmission antenna 21 a to the surface acoustic wave device 24.

Thereby, in the stirrer 20, the drive signal of the frequency f1 andthat of the frequency f2 are alternately input to the surface acousticwave device 24 during the stopping time Ts in which the reaction wheel 6stops as shown in FIG. 24. Therefore, every time the reaction wheel 6 ofthe automatic analyzer 1 stops, the drive signals input to the surfaceacoustic wave device 24 are alternately changed between that of thefrequency f1 and that of the frequency f2, and the transducers 24 b and24 c generating the sound wave are self-selectively switched.

As a result, in the stirrer 20, a sound wave Wa1 of the frequency f1 anda sound wave Wa2 of the frequency f2 alternately leak from thetransducer 24 b located on the upper side and from the transducer 24 clocated on the lower side, respectively, into the mixed liquid Lm andthe acoustic flow is generated, as shown in FIG. 25. Therefore, themixed liquid Lm of the reagent and the specimen held in the reactionvessel 7 is efficiently stirred from the bottom portion of the reactionvessel 7 to the gas-liquid interface while minimizing waste of energy,so that sufficient reaction of the reagent and the specimen is assured.In this case, the control unit 16 may perform the photometry of thereaction liquid at the initial position (in the vicinity of the opening7 e) of the photometry unit 10 without controlling the photometricposition, or may perform the photometry of the reaction liquid aftercontrolling the photometric position by moving downward the photometryunit 10 from the initial position thereof along the vertical directionof the reaction vessel 7. Meanwhile, a switching time of the frequenciesf1 and f2 is not necessarily 1:1, and may be appropriately set andchanged according to nature or the liquid amount of the specimen.

Also, the automatic analyzer 1 of the first embodiment may be configuredto supply the electrical power from the driver 20 to the surfaceacoustic wave device 22 through a fixed line by a contact pin 21 dprovided on the inner surface of the concave portion 6 a of the reactionwheel 6, as shown in FIG. 26. At this time, the surface acoustic wavedevice 22 forms a contact pad 22 d contacting the contact pin 21 d inplace of the antenna 22 c formed on the piezoelectric substrate 22 a, asshown in FIG. 27.

As described above, in the automatic analyzer 1 of the first embodiment,the control unit 16 controls the position of the photometry unit 10according to the position at which the liquid is held in the reactionvessel 7, so that the photometric position may be controlled inaccordance with the position of the liquid held in the reaction vessel7, and this allows the photometry of the liquid held in the reactionvessel 7 even when the liquid is not introduced to the bottom portion ofthe reaction vessel as in the conventional analyzer.

Next, a second embodiment of the analyzer of the present invention willbe described in detail with reference to the drawings. In the automaticanalyzer of the first embodiment, the control unit 16 has decided thevertical position and the photometric position of the photometry unit 10based on the dispensing amounts of the specimen and the reagent inputfrom the specimen dispensing mechanism 5 and the reagent dispensingmechanism 12, respectively. On the other hand, in the automatic analyzerof the second embodiment, the position of the liquid held in the vesselis detected by the surface acoustic wave device, which is the stirringmeans.

FIG. 28 is a perspective view showing the automatic analyzer of thesecond embodiment together with a schematic configuration diagram of thereaction vessel, a part of the reaction wheel, and the stirrer. FIG. 29is a front view showing the surface acoustic wave device used in thereaction vessel shown in FIG. 28 and used for detecting the position ofthe liquid held in the reaction vessel. Herein, a basic configuration ofthe automatic analyzer of the second embodiment is the same as that ofthe automatic analyzer of the first embodiment. Therefore, in theautomatic analyzer of each embodiment to be described later, the samereference numeral is used for the same component as the automaticanalyzer of the first embodiment.

The automatic analyzer of the second embodiment is provided with aposition detector 25, which is obtained by serially connecting areflection measuring unit 26 between the drive circuit 21 b and the RFtransmission antenna 21 a, as shown in FIG. 28. The position detector 25has the reflection measuring unit 26, a surface acoustic wave device 27and the controller 21 c, and doubles as the stirring means for stirringthe liquid held in the reaction vessel.

The reflection measuring unit 26 is a measuring section for measuringelectrical characteristics of transducers 27 b to 27 d, which are thesound generating elements of the surface acoustic wave device 27. Thereflection measuring unit 26 is for measuring reflectivity of electricalenergy (electrical power) reflected by and returned from the transducers27 b to 27 d with respect to the electrical power generated in the drivecircuit 21 b and output from the RF transmission antenna 21 a to thesurface acoustic wave device 27, and a standing wave ratio (SWR)calculator is used, for example. The reflection measuring unit 26outputs the measured reflectivity of electrical power to the controller21 c as a reflection signal. Herein, the reflection measuring unit 26may measure at least one of values regarding impedance, voltage andcurrent in addition to the reflectivity of the electrical power from thetransducers 27 b to 27 d, which are the sound generating elements, aslong as this may measure the electrical characteristics of thetransducers 27 b to 27 d.

The surface acoustic wave device 27 is sound wave generating meanshaving a plurality of sound generating elements, and as shown in FIG.29, the transducers 27 b to 27 d, which are the sound generatingelements formed of the interdigital transducers (IDTs), are formed onthe piezoelectric substrate 27 a formed of the same material as that ofthe piezoelectric substrate 22 a, and the transducers 27 b to 27 d areparallelly connected by an antenna 27 e. At this time, the surfaceacoustic wave device 27 sets the center frequencies of the transducers27 b to 27 d to f1 to f3 (f1<f2<f3) and is attached to the side wall 7 bof the reaction vessel 7 through the acoustic matching layer.

The controller 21 c is a determination control unit for determiningpresence or absence of the liquid at the position of each of thetransducers 27 b to 27 d, which are the sound generating elements, byutilizing the difference in the electrical characteristics measured atthe reflection measuring unit 26. The controller 21 c determinespresence or absence of the liquid held in the reaction vessel based onthe reflection signal input from the reflection measuring unit 26,detects the position of the liquid, and decides the transducer to beused to stir the liquid out of the transducers 27 b to 27 c. At thistime, the controller 21 c, which has decided the transducer to be used,outputs the control signal to the drive circuit 21 b and changes theoscillation frequency so as to drive the decided transducer with thecenter frequency.

The position detector 25 thus configured detects presence or absence andthe position of the liquid held in the reaction vessel 7 by a positiondetecting method to be described later. That is, the position detectingmethod by the position detector 25 includes a process to change withtime the frequency of the drive signal of the surface acoustic wavedevice 27 output by the drive circuit 21 b to the RF transmissionantenna 21 a and to individually generate the sound wave from thetransducers 27 b to 27 d, a process to measure the reflectivities of thedrive signal from each of the transducers 27 b to 27 d based on theindividually generated sound waves, and a process to determine presenceor absence of the liquid at the position of each of the transducers 27 bto 27 d based on the difference in the measured reflectivities. Theposition detector 25 may detect presence or absence and the position ofthe liquid held in the reaction vessel 7 by this position detectingmethod.

Herein, the position detector 25 linearly changes with time thefrequency of the drive signal of the surface acoustic wave device 27,output by the drive circuit 21 b to the RF transmission antenna 21 a,for example, as shown in FIG. 30, when executing the position detectingmethod. In such a case, in the reaction vessel 7, the liquid holdingsection 7 d is in an empty state, as shown in FIG. 31, if the specimenand reagent are not dispensed. At this time, in the position detector25, as shown in FIG. 30, when the frequency of the drive signal ischanged, the frequency becomes f1, f2 and f3 at times T1, T2 and T3, andthe transducers 27 b to 27 d are driven in the order of transducers 27b, 27 c and 27 d. However, in the reaction vessel 7, since the liquidholding section 7 d is empty, the generated sound wave does not leakinto the liquid and a part of electrical power output from the drivecircuit 21 b is sequentially reflected from the transducers 27 b to 27d. Therefore, the reflection measuring unit 26 outputs the reflectionsignals from the transducers 27 b to 27 d in which the reflectivities ofthe drive signals of the frequencies f1, f2 and f3 become the smallestat the times T1, T2 and T3, as shown in FIG. 32, to the controller 21 c.

On the other hand, in a case in which the dispensing amounts of thespecimen and the reagent are small, in the reaction vessel 7, the liquidLq is held in the vicinity of the opening 7 e by the surface tension, asshown in FIG. 33. At this time, in the position detector 25, as shown inFIG. 30, when the frequency of the drive signal is changed, since thetransducer 27 b is the closest to the liquid Lq, the amount of the soundwave generated by the transducer 27 b leaking into the liquid is thelargest, and the amount of the sound wave generated by the transducers27 c and 27 d leaking into the liquid is smaller. Therefore, thereflection measuring unit 26 outputs the reflection signal (frequencyf1) in which the reflectivity from the transducer 27 b becomessignificantly smaller than the reflectivities from the transducers 27 cand 27 d, as shown in FIG. 34, to the controller 21 c. At this time, thereflectivities of the drive signals (frequencies f2 and f3) reflectedfrom the transducers 27 c and 27 d are larger than the reflectivity ofthe drive signal of the frequency f1 and substantially equal to thereflectivity of the drive signals (frequencies f2 and f3) of thetransducers 27 c and 27 d in FIG. 32 because the liquid does not existin the liquid holding section 7 d corresponding to the transducers 27 can 27 d and the sound wave does not leak into the liquid.

On the other hand, if the specimen and the reagent are dispensed inlarge volume, in the reaction vessel 7, the liquid Lq is held from thevicinity of the opening 7 e to near the lower portion of the liquidholding section 7 d, as shown in FIG. 35. In such a state, the positionsof the transducers 27 b to 27 d and the position of the liquid Lq areclose to each other. Therefore, in the position detector 25, as shown inFIG. 30, when the frequency of the drive signal is changed, the soundwave generated from each of the transducers 27 b to 27 d leaks into theliquid and the reflectivities of the drive signals from the transducers27 b to 27 d become smaller. As a result, the reflection measuring unit26 outputs the reflection signal in which the reflectivities of thedrive signals (frequencies f2 and f3) of the transducers 27 c and 27 dalso become the smallest in addition to the reflectivity of the drivesignal (frequency f1) of the transducer 27 b, as shown in FIG. 36 to thecontroller 21 c.

Further, there is a case in which the liquid Lq intrudes into the bottomportion of the reaction vessel 7, as shown in FIG. 37, due to theextremely small surface tension or the large density ρ, for example,even though the dispensing amounts of the specimen and the reagent aremoderate. In such a case, the position of the transducer 27 d and theposition of the liquid Lq are close to each other. Therefore, in theposition detector 25, as shown in FIG. 30, when the frequency of thedrive signal is changed, the sound wave generated from the transducer 27d leaks into the liquid and leaking amounts of the sound waves generatedby the transducers 27 b and 27 c become smaller. As a result, thereflection measuring unit 26 outputs the reflection signal in which thereflectivity of the drive signal (frequency f3) of the transducer 27 dis significantly smaller than the reflectivities of the drive signals(frequencies f1 and f2) of the transducers 27 b and 27 c, as shown inFIG. 38, to the controller 21 c.

From the above description, the position detector 25 may detect theposition of the liquid held in the reaction vessel 7, in addition topresence or absence of dispensing of the liquid to the reaction vessel 7(presence or absence of the liquid), by determining a magnitude of thereflectivities of the drive signal output from the reflectivity measure26 to the controller 21 c, at the controller 21 c.

Therefore, the automatic analyzer of the second embodiment may optimallystir the liquid held in the reaction vessel 7 by allowing the controlunit 16 to select the transducers 27 b to 27 d to be driven according tothe position of the liquid in the reaction vessel 7 detected by thecontroller 21 c of the position detector 25. At this time, the automaticanalyzer of the second embodiment adjusts the vertical position of thephotometry unit 10 by means of the driver Dr by the control unit 16according to the position of the liquid detected by the positiondetector 25, in addition to the photometric position control performedby the automatic analyzer of the first embodiment, to control thephotometric position in accordance with the position of the liquid,thereby performing the photometry.

Accordingly, in the automatic analyzer of the second embodiment, thecontrol unit 16 controls the position of the photometry unit 10according to the position at which the liquid is held in the reactionvessel 7, so that it is possible to control the photometric position inaccordance with the position of the liquid held in the reaction vessel7, and this allows for the photometry of the liquid held in the reactionvessel 7 even when the liquid is not introduced to the bottom portion ofthe reaction vessel as in the conventional analyzer.

Especially, the automatic analyzer of the second embodiment allows forthe photometry by the photometry unit 10 at the position of the liquidheld in the reaction vessel 7, by allowing the position detector 25 todetect the position at which the liquid is held in the reaction vessel7. In addition, the position detector 25 and the position detectingmethod of the second embodiment may detect the position of the liquidheld in the reaction vessel 7 with a simple configuration. Also, theautomatic analyzer of the second embodiment allows for the photometry atthe position of the liquid held in the reaction vessel 7. Further, theposition detector 25 and the position detecting method of the secondembodiment may detect the position of the liquid from outside thereaction vessel 7 without contacting the liquid in the reaction vessel7, so that this may prevent another substance from being mixed into thereaction vessel 7 when used in the automatic analyzer.

Herein, although the automatic analyzer of the second embodimentlinearly changes with time the frequency of the drive signal of thesurface acoustic wave device 27 used in the position detector 25, asshown in FIG. 30, it is possible to gradually change the frequency ofthe drive signal as the frequency f1 until the time T1, the frequency f2between the times T1 and T2, and the frequency f3 after the time T2.

Meanwhile, in the position detector 25, although three transducers 27 bto 27 d are used as the sound generating elements of the surfaceacoustic wave device 27, the number of the sound generating elements isnot limited to three and more accurate position detection becomespossible by increasing the number thereof to be set according to thesize of the reaction vessel.

Next, a third embodiment of the analyzer of the present invention willbe described in detail with reference to the drawings. Although thesurface acoustic wave device has been attached to the reaction vessel inthe automatic analyzers of the first and second embodiments, theautomatic analyzer of the third embodiment is configured such that thesurface acoustic wave device located in the vicinity of the reactionvessel is disjunctive. FIG. 39 is a block diagram showing theconfiguration of the automatic analyzer of the third embodiment byshowing the cross section of the reaction vessel and the reaction table.FIG. 40 is a plan view of a part of the reaction table used in theautomatic analyzer in FIG. 39 together with the surface acoustic wavedevice and a driver thereof.

An automatic analyzer 30 is provided with a specimen dispensing section31, a reagent dispensing section 32, a reaction table 33, a surfaceacoustic wave device 36, a photometry unit 38, a control unit 39 and astirring unit 40, as shown in FIG. 39.

The specimen dispensing section 31 dispenses the specimen accommodatedin a specimen storage unit 31 a to a reaction vessel 35 by a specimennozzle 31 b, as shown in FIG. 39. The reagent dispensing section 32dispenses the reagent accommodated in a reagent storage unit 32 a to thereaction vessel 35 by a reagent nozzle 32 b. The specimen dispensingsection 31 and the reagent dispensing section 32 are separately drivenby drive means and move above an outer circumference of the reactiontable 33 in a two-dimensional direction along the surface thereof. Thespecimen dispensing section 31 and the reagent dispensing section 32output the dispensing amounts of the specimen and the reagent dispensedto the reaction vessel 35 to the control unit 39.

The reaction table 33 is rotated by a drive motor 34, and a plurality ofconcave-shaped holders 33 a arranged along the circumferential directionare provided on the outer circumference thereof, as shown in FIGS. 39and 40. The reaction vessel 35 is detachably accommodated in the holder33 a. Also, in the reaction table 33, an abutting window 33 c formed ofan opening is formed in a central portion of an outer surface of a sidewall 33 b and a photometric window 33 e extending in the verticaldirection is formed on a side wall 33 d adjacent to the side wall 33 b.At this time, the holder 33 a is formed such that the side wall 33 b onwhich the abutting window 33 c is formed and the side wall 33 b facingthe same are inclined at 45 degrees relative to the radial direction,and the two side walls 33 d forming the photometric window 33 e areformed so as to be parallel to each other.

Herein, although a plurality of holders 33 a are provided on the outercircumference of the reaction table 33 along the circumferentialdirection thereof, as shown in FIG. 40, in FIGS. 42 to 44, forconvenience of clearly showing the configuration, only one holder 33 ais shown. Also, as shown in FIG. 39, the surface acoustic wave device 36and the photometry unit 38 are arranged on opposed positions in adiameter direction of the reaction table 33; however, in FIG. 40, thesurface acoustic wave device 36 is shown to be arranged in the vicinityof the photometry unit 38 to clearly and simply show the arrangement ofthe surface acoustic wave device 36 and the photometry unit 38.

The reaction vessel 8 in a rectangular tubular shape shown in FIGS. 17and 18 described in the first embodiment for holding the small amount ofliquid of a few nanoliters (nL) to several tens of microliters (μL) inthe liquid holding section 35 d is used as the reaction vessel 35;however, the surface acoustic wave device 36 is not attached to the sidewall 35 b but is arranged in the vicinity thereof.

The surface acoustic wave device 36 is the stirring means for stirringthe liquid held in the reaction vessel 35 by the sound wave (surfaceacoustic wave: SAW), and as shown in FIGS. 40 to 42, a transducer 36 b,which is the sound generating element formed of the interdigitaltransducer (IDT), is formed on a piezoelectric substrate 36 a, and isdriven by the electrical power supplied from a drive circuit 42 (seeFIG. 39) of the stirring unit 40. Also, the surface acoustic wave device36 is attached to a tip end of an arm 41 a driven in a directionindicated by an arrow by a motor 41, as shown in FIG. 39, and isdisjunctive to a side wall 35 b of the reaction vessel 35 through theabutting window 33 c formed on the side wall 33 b. At this time, thesurface acoustic wave device 36 is arranged at an inclination so as toface the side wall 35 b of the reaction vessel 35 held by the holder 33a, and acoustic matching liquid held in a liquid storage unit 37 a of aliquid dispensing section 37 arranged in the upper vicinity thereof isdropped from a nozzle 37 b.

As shown in FIG. 39, the photometry unit 38 has a light source 38 a foremitting a bundle of light (see FIG. 40) of analytical light (340 to 800nm) for analyzing the liquid held in the reaction vessel 35 and a lightreceiver 38 b for dispersing and receiving the bundle of lightpenetrating the liquid, arranged so as to face each other in a radialdirection of the reaction table 33 with the holder 33 a interposedtherebetween. In the photometry unit 38, a vertical position(photometric position) of the light source 38 a and the light receiver38 b is controlled by the driver Dr provided in the lower portion andcontrolled by the control unit 39. Herein, the reaction vessel 35 ofwhich photometry at the photometry unit 38 is finished is transferred tothe cleaner and is cleaned, and after that, used again for analyzing thenew specimen.

The control unit 39 is connected to the specimen dispensing section 31,the reagent dispensing section 32, the drive motor 34, the liquiddispensing section 37, the photometry unit 38 and the stirring unit 40,as shown in FIG. 39, and the microcomputer or the like incorporating amemory and a timer for storing the analytical result is used, forexample. The control unit 39 controls operation of each section of theautomatic analyzer 30 to analyze constituent concentration or the likeof the specimen based on information of the transmitted light outputfrom the light receiver 38 b. Also, the control unit 39 is provided withthe input unit such as the keyboard and the mouse for performingoperation of inputting the inspection item or the like and the displaypanel for displaying the analytical content, the alert or the like.

Herein, the control unit 39 controls characteristics (frequency,intensity, phase, characteristics of wave), waveforms (sine wave,triangle wave, rectangular wave, burst wave, or the like) or modulations(amplitude modulation, frequency modulation) or the like of the soundwave generated by the surface acoustic wave device 36, when controllingthe stirring unit 40. Also, the control unit 39 may switch the frequencyof the oscillation signal oscillated by the drive circuit 42 accordingto the incorporated timer.

The control unit 39 obtains in advance the table and the function fordeciding the vertical position, that is, the photometric position, ofthe photometry unit 38 based on the dispensing amounts of the specimenand the reagent input from the specimen dispensing section 31 and thereagent dispensing section 32, respectively, and controls the positionof the driver Dr based on the table and the function, therebycontrolling the photometric position of the photometry unit 38. Herein,in the control unit 39, when the measurement item of the specimen andthe position information of the reaction vessel 35 are input from theinput unit, signals corresponding to the measurement item and theposition information of the reaction vessel 35, which have been input,are input from the input unit. The control unit 39 allows the specimendispensing section 31 and the reagent dispensing section 32 to dispensethe specimen and the reagent to the specified reaction vessel 35 in apredetermined amount, based on these signals.

At this time, the specimen dispensing section 31 and the reagentdispensing section 32 output the dispensing amount signals regarding thedispensing amounts of the specimen and the reagent dispensed to thereaction vessel 35 to the control unit 39, as described above. Thecontrol unit 39 outputs the dispensing amount signal to the stirringunit 40 and, reads the photometric position measured in advance andstored regarding the reaction vessel 35 based on the dispensing amountsignals thus input, and controls the photometric position of thephotometry unit 38 by means of the driver Dr.

The stirring unit 40 is the section for stirring the liquid held in thereaction vessel 35 by driving the surface acoustic wave device 36 underthe control of the control unit 39, and has the motor 41 and the drivecircuit 42 as shown in FIG. 39.

The motor 41 drives the arm 41 a, moves the surface acoustic wave device36 in a direction indicated by an arrow shown in FIG. 39, and allows thesame to abut the side wall 35 b of the reaction vessel 35 through theabutting window 33 c of the holder 33 a at the time of stirring (seeFIG. 43), under the control of the control unit 39.

The drive circuit 42 has the oscillation circuit capable of programmablychanging the oscillation frequency based on the control signal from thecontrol unit 39, amplifies the oscillation signal of high frequency ofabout several tens of MHz to several hundreds of MHz and outputs thesame to the surface acoustic wave device 36 as the drive signal, as wellas gradually switches the drive frequency of the drive signal based onthe control signal from the control unit 39.

The automatic analyzer 30 configured in this manner analyzes thespecimen dispensed to the reaction vessel 35 by the photometric methodto be described below including a process to control the photometricposition at which the photometry of the liquid is performed according tothe holding position at which the liquid is held in the reaction vessel35, and a process to perform the photometry of the liquid at thecontrolled photometric position.

First, the automatic analyzer 30 rotates the reaction table 33 and stopsthe holder 33 a holding the reaction vessel 35 to be dispensed at areagent dispensing position under the control of the control unit 39.Next, in the automatic analyzer 30, the reagent dispensing section 32dispenses a first reagent from above the reaction vessel 35 to theopening 35 a, by the reagent nozzle 32 b under the control of thecontrol unit 39. At this time, since the capacity of the reaction vessel35 is as extremely small as a few nanoliters (nL) to several tens ofmicroliters (μL), the first reagent is held in the vicinity of theopening 35 e through air at the lower portion according to at least oneof the kind or the amount thereof and the form or the material of thereaction vessel 35. The control unit 39 controls the vertical position(photometric position) of the photometry unit 38 by the driver Dr basedon the dispensing amount of the first reagent output by the reagentdispensing section 32.

Next, the automatic analyzer 30 rotates the reaction table 33 to movethe reaction vessel 35 to which the first reagent has been dispensed tothe photometry unit 38 under the control of the control unit 39.Thereby, in the reaction vessel 35, the analytical light emitted fromthe light source 38 a is applied from the photometric window 33 e of theholder 33 a and the photometry of the bundle of light penetrated thefirst reagent is performed by the light receiver 38 b at the appropriatephotometric position in the vicinity of the opening 35 e. The lightreceiver 38 b outputs light information regarding the received bundle oflight to the control unit 39. The control unit 39 calculates lightabsorbance of the first reagent based on the light information andstores the same.

After blank photometry regarding the first reagent is finished in thismanner, the automatic analyzer 30 drives the drive motor 34 to rotatethe reaction table 33 and moves the reaction vessel 35 to which thefirst reagent has been dispensed to the specimen dispensing section 31under the control of the control unit 39. Next, the automatic analyzer30 dispenses the specimen from the specimen nozzle 31 b on the firstreagent held in the vicinity of the opening 35 e of the reaction vessel35 under the control of the control unit 39. At this time, the controlunit 39 controls the vertical position (photometric position) of thephotometry unit 38 by the driver Dr based on the dispensing amount ofthe specimen output from the specimen dispensing section 31.

Next, the automatic analyzer 30 drives the transducer 36 b by the drivecircuit 42 and stirs the first reagent and the specimen by the generatedsound wave (surface acoustic wave) to react them under the control ofthe control unit 39. Thereafter, the automatic analyzer 30 drives thedrive motor 34 to rotate the reaction table 33 and moves the reactionvessel 35 to the photometry unit 38, under the control of the controlunit 39. Thereby, in the reaction vessel 35, the photometry of reactionliquid obtained by reacting the first reagent and the specimen isperformed at the appropriate photometric position in the vicinity of theopening 35 e. The control unit 39 calculates the light absorbance of thereaction liquid obtained by reacting the first reagent and the specimenbased on the light information obtained by the light receiver 38 b andstores the same.

Next, the automatic analyzer 30 drives the drive motor 34 to rotate thereaction table 33 and moves the reaction vessel 35 holding the reactionliquid of the first reagent and the specimen to the reagent dispensingsection 32, under the control of the control unit 39. After that, theautomatic analyzer 30 dispenses a second reagent from the reagent nozzle32 b on the reaction liquid held in the vicinity of the opening 35 e ofthe reaction vessel 35 under the control of the control unit 39. At thistime, the control unit 39 controls the photometric position of thephotometry unit 38 based on the dispensing amount of the second reagentoutput by the reagent dispensing section 32. Next, the automaticanalyzer 30 drives the motor 41 to run out the arm 41 a and allows thesame to abut the side wall 35 b of the reaction vessel 35, and drivesthe transducer 36 b by the drive circuit 42 to stir the reaction liquidof the first reagent and the specimen and the second reagent by thegenerated sound wave (surface acoustic wave) to react them under thecontrol of the control unit 39.

After that, the automatic analyzer 30 drives the motor 41 to draw in thearm 41 a, which has been run out, and drives the drive motor 34 torotate the reaction table 33 to move the reaction vessel 35 to thephotometry unit 38, under the control of the control unit 39. Thereby,in the reaction vessel 35, the photometry of the reaction liquidobtained by reacting the reaction liquid of the first reagent and thespecimen with the second reagent is performed at the appropriatephotometric position in the vicinity of the opening 35 e of the reactionvessel 35. The control unit 39 calculates the light absorbance of thereaction liquid obtained by reacting the reaction liquid of the firstreagent and the specimen with the second reagent based on the lightinformation obtained by the light receiver 38 b and calculates theconstituent concentration or the like of the specimen based on the lightabsorbance of the first reagent and the light absorbance of the mixedliquid of the first reagent and the specimen measured in advance. Then,the reaction vessel 35 in which photometry at the photometry unit 38 isfinished is transferred to the cleaner and the reaction liquid isdischarged and is cleaned, and thereafter, used again for analyzing thenew specimen.

Herein, the automatic analyzer 30 drops acoustic matching liquid Lm onthe surface of the surface acoustic wave device 36 by the nozzle 37 b ofthe liquid dispensing section 37 as shown in FIG. 42 under the controlof the control unit 39 upon stirring of the liquid by the surfaceacoustic wave device 36. At this time, the reaction vessel 35 holdingthe liquid Lq is inserted to the holder 33 a in the vicinity of theopening 35 e. Next, the automatic analyzer 30 runs out the arm 41 a bythe motor 41 and allows the surface acoustic wave device 36 to abut theside wall 35 b of the reaction vessel 35 through the abutting window 33c under the control of the control unit 39, as shown in FIG. 43.Thereby, a thin film of the acoustic matching liquid Lm is arrangedbetween the surface acoustic wave device 36 and the side wall 35 b, sothat the sound wave (surface acoustic wave) generated by the surfaceacoustic wave device 36 leaks into the liquid Lq held in the reactionvessel 35 through the side wall 35 b and the liquid Lq is stirred by theleaked sound wave Wa.

In this manner, in the automatic analyzer 30 of the third embodiment,the control unit 39 controls the position of the photometry unit 38according to the position at which the liquid of the reaction vessel 35is held, it is possible to control the photometric position inaccordance with the position of the liquid held in the reaction vessel35, and this allows for the photometry of the liquid held in thereaction vessel 35 even though the liquid is not introduced to thebottom portion of the reaction vessel 35 as in the conventionalanalyzer. At this time, the automatic analyzer 30 performs thephotometry of the liquid in the vicinity of the opening 35 e in a statein which the liquid is held in the vicinity of the opening 35 e of thereaction vessel 35. Therefore, the automatic analyzer 30 does notrequire means for sending the liquid to the inside the reaction vessel35.

However, the position at which the reaction vessel 35 holds the liquidincluding the reagent R and the specimen S varies according to at leastone of the kind or the amount of the liquid and the form or the materialof the reaction vessel 35. Therefore, in such a case, the control unit39 reads the photometric position stored in advance based on thedispensing amount signals regarding the dispensing amounts of thespecimen and the reagent input from the specimen dispensing section 31and the reagent dispensing section 32, respectively, and controls thephotometric position by the photometry unit 38 by means of the driverDr.

Herein, the acoustic matching liquid Lm is easy to flow when viscositythereof is low. Therefore, in the holder 33 a, it is preferable toprovide a skirt portion 33 f on a lower portion of the abutting window33 c side for receiving the acoustic matching liquid Lm dropped on thesurface acoustic wave device 36, as shown in FIG. 44.

Next, a fourth embodiment of the analyzer of the present invention willbe described in detail with reference to the drawings. In the automaticanalyzer of the first embodiment, the photometric positions of the lightsource and the light receiver of the photometry unit have beencontrolled collectively by one drive means. On the other hand, in theautomatic analyzer of the fourth embodiment, the photometric positionsof the light source and the light receiver are independently controlledby independent drive means. FIG. 45 is a schematic view showing aschematic configuration of the automatic analyzer of the fourthembodiment together with the cross section of the reaction vessel.

In the automatic analyzer 50, a light source 10 a and a light receiver10 b are provided on the driver 51 and the driver 52, respectively, suchthat the vertical position (photometric position) thereof iscontrollable, regarding the photometry unit 10 provided on the positionsradially facing each other with the concave portion 6 a of the reactionwheel 6 interposed therebetween, as shown in FIG. 45. Herein, thedrivers 56 a and 57 a are driven by the control unit 16 to individuallycontrol the vertical positions (photometric positions) of the lightsource 10 a and the light receiver 10 b. The dispensing amounts of thespecimen and the reagent are input from the specimen dispensingmechanism 5 and the reagent dispensing mechanism 12, respectively, tothe control unit 16. The control unit 16 obtains in advance the tableand the function for deciding the vertical positions, that is, thephotometric positions of the light source 10 a and the light receiver 10b based on the dispensing amounts, and controls the operations of thedrivers 51 and 52 based on the table and the function, therebycontrolling the photometric positions.

The automatic analyzer 50 analyzes the liquid held in the reactionvessel 7 in the same manner as the photometric method of the automaticanalyzer 1 including the process to control the photometric position atwhich the photometry of the liquid is performed according to the holdingposition at which the liquid is held in the reaction vessel 7, and theprocess to perform the photometry of the liquid at the controlledphotometric position.

At this time, as shown in FIG. 45, when the dispensing amount of theliquid Lq is small, since the capacity of the reaction vessel 7 is asextremely small as a few nanoliters (nL) to several tens of microliters(μL), the liquid Lq is held in the vicinity of the opening 7 e due tothe large effect of the surface tension. Therefore, the control unit 16obtains the amount of the liquid Lq from the dispensing amounts of thespecimen and the reagent input from the specimen dispensing mechanism 5and the reagent dispensing mechanism 12, respectively, and holds thelight source 10 a and the light receiver 10 b at the initial positionsfrom the table and the function for deciding the photometric positionobtained in advance based on the obtained amount of liquid Lq withoutdriving the drivers 51 and 52. Then, the automatic analyzer 50 performsthe photometry of the liquid Lq in the vicinity of the opening 7 e bythe bundle of light BL emitted from the light source 10 a, as shown inFIG. 45, in a state in which the light source 10 a and the lightreceiver 10 b are held at the initial positions.

However, the position at which the reaction vessel 7 holds the liquid Lqincluding the reagent and the specimen varies according to at least oneof the kind or amount of the liquid Lq and the form or the material ofthe reaction vessel 7. Therefore, when the dispensing amounts of thereagent and the specimen are large and the amount of the liquid Lq islarge, for example, as shown in FIG. 46, in the reaction vessel 7, theliquid Lq intrudes halfway into the liquid holding section 7 d from thevicinity of the opening 7 e.

Therefore, the control unit 16 may perform the photometry of the liquidLq in the vicinity of the opening 7 e, which is the initial position ofthe photometry unit 10 without controlling the photometric position, ormay perform the photometry of the liquid Lq after controlling thephotometric position. In this case, the control unit 16 reads thephotometric position stored in advance based on the dispensing amountsignals regarding the dispensing amounts of the specimen and the reagentinput from the specimen dispensing mechanism 5 and the reagentdispensing mechanism 12, respectively, and moves (lowers) the lightsource 10 a and the light receiver 10 b from the initial positionthereof to the central portion in the vertical direction of the reactionvessel 7 by means of the drivers 51 and 52, respectively, by a distanceL1, thereby controlling the photometric positions. Then, the automaticanalyzer 50 performs the photometry of the liquid Lq held in thereaction vessel 7 at the photometric position moved downward by thebundle of light BL emitted from the light source 10 a, as shown in FIG.46.

In this manner, in the automatic analyzer 50 of the fourth embodiment,since the control unit 16 individually controls the position of thelight source 10 a and the light receiver 10 b according to the positionof the liquid held in the reaction vessel 7, it is possible to controlthe photometric positions in accordance with the position of the liquidheld in the reaction vessel 7, and this allows for the photometry of theliquid held in the reaction vessel 7 even though the liquid is notintroduced to the bottom portion of the reaction vessel as in theconventional analyzer.

Next, a fifth embodiment of the analyzer of the present invention willbe described in detail with reference to the drawings. The automaticanalyzer of the fourth embodiment controls the photometric positions ofthe light source and the light receiver by moving them in the verticaldirection by the independent drive means. On the other hand, theautomatic analyzer of the fifth embodiment controls the photometricpositions of the liquid by independent movable mirrors. FIG. 47 is aschematic view showing a schematic configuration of the automaticanalyzer of the fifth embodiment together with the cross section of thereaction vessel.

In an automatic analyzer 55, movable mirrors 56 b and 57 b are providedon drivers 56 a and 57 a of drive sections 56 and 57, respectively, suchthat the angle of inclination is controllable by the drivers 56 a and 57a, respectively. Herein, the movable mirrors 56 b and 57 b are driven bythe control unit 16 based on the dispensing amounts of the specimen andthe reagent to the reaction vessel 7 by the specimen dispensingmechanism 5 and the reagent dispensing mechanism 12, respectively, inputto the control unit 16, and the angles of inclination are controlled.The control unit 16 controls, by the movable mirrors 56 ba and 57 b, theposition at which the bundle of light BL emitted from the light source10 a penetrates the liquid according to the position of the liquid heldin the reaction vessel 7.

Therefore, as in the first embodiment, the control unit 16 obtains inadvance the table and the function for deciding the position in thevertical direction at which the bundle of light BL penetrates thereaction vessel 7 based on angles of inclination θ1 and θ2 of themovable mirrors 56 b and 57 b by the drivers 56 a and 57 a, based on thedispensing amounts of the specimen and the reagent input from thespecimen dispensing mechanism 5 and the reagent dispensing mechanism 12to the reaction vessel 7, and controls the operations of the drivers 56a and 57 a based on the table and the function, thereby controlling thephotometric position. At this time, due to the inclination of themovable mirrors 56 b and 57 b, the bundle of light BL penetrating theliquid held in the reaction vessel 7 also inclines, the light pathlength when penetrating the liquid changes, and also an incident angleθi of the light entering the light receiver 10 b, accordingly theincident light amount changes. Therefore, a data correction unit 58 forcorrecting the light path length and the incident light amount isprovided with the automatic analyzer 55.

The microcomputer or the like, for example, is used as the datacorrection unit 58, which obtains in advance and stores a correctionvalue of the light path length and the incident light amount based onthe incident angle of the light entering the reaction vessel 7 and theincident angle θi entering the light receiver 10 b from the angles ofinclination of the movable mirrors 56 b and 57 b input by the controlunit 16 to the drivers 56 a and 57 a based on the dispensing amount ofthe liquid. The data correction unit 58 reads the correction values ofthe light path length and the incident light amount when the angles ofinclination θ1 and θ2 of the movable mirrors 56 b and 57 b are inputfrom the control unit 16, and outputs the values to the control unit 16.The control unit 16 utilizes the correction values to correct the lightabsorbance by the photometry unit 10.

The automatic analyzer 55 analyzes the liquid held in the reactionvessel 7 in the same manner as the photometric method of the automaticanalyzer 1 including the process to control the photometric position atwhich the photometry of the liquid is performed according to the holdingposition at which the liquid is held in the reaction vessel 7, and theprocess to perform the photometry of the liquid at the controlledphotometric position.

At this time, as shown in FIG. 47, when the dispensing amount of theliquid Lq is small, since the capacity of the reaction vessel 7 is asextremely small as a few nanoliters (nL) to several tens of microliters(μL), the liquid Lq is held in the vicinity of the opening 7 e due tothe large effect of the surface tension. Therefore, the control unit 16,which has obtained the amount of the liquid Lq from the dispensingamounts of the specimen and the reagent input from the specimendispensing mechanism 5 and the reagent dispensing mechanism 12,respectively, holds the movable mirrors 56 b and 57 b at the initialpositions from the table and the function obtained in advance based onthe amount of the obtained liquid Lq without driving the drivers 56 aand 57 a. Then, the automatic analyzer 55 performs the photometry of theliquid Lq in the vicinity of the opening 7 e by the bundle of light BLemitted from the light source 10 a, as shown in FIG. 47, in a state inwhich the movable mirrors 56 b and 57 b are held at the initialpositions.

However, the position at which the reaction vessel 7 holds the liquid Lqincluding the reagent and the specimen varies according to at least oneof the kind or the amount of the liquid Lq and the form or the materialof the reaction vessel 7. Therefore, when the dispensing amounts of thereagent and the specimen are large and the amount of the liquid Lq islarge, for example, as shown in FIG. 48, in the reaction vessel 7, theliquid Lq might intrude halfway into the liquid holding section 7 d fromthe vicinity of the opening 7 e.

Therefore, when the liquid Lq intrudes halfway into the liquid holdingsection 7 d from the vicinity of the opening 7 e, as shown in FIG. 48,the control unit 16 may perform the photometry of the liquid Lq at theinitial position of the photometry unit 10 without controlling thephotometric position, or may perform the photometry of the liquid Lqafter controlling the photometric position. In this case, the controlunit 16 reads the photometric position stored in advance based on thedispensing amount signals regarding the dispensing amounts of thespecimen and the reagent input from the specimen dispensing mechanism 5and the reagent dispensing mechanism 12, respectively, and inclines themovable mirrors 56 b and 57 b from the initial positions thereof by theangles of inclination θ1 and θ2 by means of the drivers 56 and 57 a,respectively. Thereby, the control unit 16 lowers the position in thevertical direction at which the bundle of light BL penetrates thereaction vessel 7, thereby controlling the photometric position. Then,the automatic analyzer 55 performs the photometry of the liquid Lq heldin the reaction vessel 7 at the photometric position moved downward bythe bundle of light BL emitted from the light source 10 a, as shown inFIG. 47.

In this manner, in the automatic analyzer 55 of the fifth embodiment,since the control unit 16 controls the photometric position by incliningthe movable mirrors 56 b and 57 b according to the position of theliquid held in the reaction vessel 7, it is possible to control thephotometric position in accordance with the position of the liquid heldin the reaction vessel 7, and this allows for the photometry of theliquid held in the reaction vessel 7 even though the liquid is notintroduced to the bottom portion of the reaction vessel as in theconventional analyzer.

Herein, the automatic analyzer 55 may change the positions of themovable mirrors 56 b and 57 b in the vertical direction from the initialpositions thereof in place of inclining the movable mirrors 56 b and 57b by the drivers 56 a and 57 a, respectively. By thus configuring, theautomatic analyzer 55 does not require to be provided with the datacorrection unit 58 because the light path length and the incident lightamount when the bundle of light BL penetrates the liquid do not change.

Sixth Embodiment

Next, a sixth embodiment of the analyzer of the present invention willbe described in detail with reference to the drawings. The automaticanalyzer of the fifth embodiment performs the photometry of the bundleof light emitted from the single light source by the single lightreceiver. On the other hand, the automatic analyzer of the sixthembodiment performs the photometry of the bundle of light emitted from aplurality of light sources by a plurality of light receivers. FIG. 49 isa schematic view showing a schematic configuration of the automaticanalyzer of the sixth embodiment together with the cross section of thereaction vessel.

In an automatic analyzer 60, a photometry unit 61 has a light sourcearray 62 formed of a plurality of LEDs 62 a and a light receiving devicearray 63 formed of a plurality of light receiving devices 63 a, as shownin FIG. 49. The automatic analyzer 60 forms the position detector of thecontrol unit 16 and the photometry unit 61, and the control unit 16becomes the detecting section for detecting the position of the liquidheld in the reaction vessel 7 based on photometric data of the lightreceiving device array 63. At this time, a plurality of LEDs 62 a and aplurality of light receiving devices 63 a are arranged along thevertical direction orthogonal to the gas-liquid interfaces M1 and M2 ofthe liquid Lq held in the reaction vessel 7. The automatic analyzer 60sequentially lights the LEDs 62 a by switching the control signal outputfrom the control unit 16 by a switch circuit 64 and outputting thesignal to the light source array 62. Concurrently, the automaticanalyzer 60 switches the control signal output from the control unit 16by the switch circuit 65 to sequentially receive the analytical lightemitted from the LEDs 62 a by the corresponding light receiving device63 a in the light receiving device array 63, thereby performing thephotometry and the position detection of the liquid Lq held in thereaction vessel 7. The photometric data received by each light receivingdevice 63 a is output to the control unit 16.

At this time, the control unit 16 obtains in advance the table and thefunction for deciding the position, that is, the photometric position ofthe liquid Lq, based on the dispensing amounts of the specimen and thereagent input from the specimen dispensing mechanism 5 and the reagentdispensing mechanism 12, respectively, and sequentially switches the LED62 a and the light receiving device 63 a based on the table and thefunction, thereby controlling the photometric position. Then, thecontrol unit 16 compares the photometric data in which the light amountdue to the absorption by the liquid Lq is small and the photometric datain which the light amount is large because the light absorption is smalldue to the absence of the liquid Lq, in the photometric data input fromeach light receiving device 63 a, and detects the position of the lightreceiving device 63 a outputting the photometric data in which the lightamount is small as the position of the liquid and sets the photometricdata of the light receiving device 63 a in which the light receivingamount is the smallest as the measurement amount of the analytical lightpenetrated the liquid Lq. In this case, the number of light receivingdevices 63 a at the position at which the liquid Lq exists may be singleor plural depending on the amount of the liquid. Also, it is possiblenot only to control the photometric position by sequentially switchingthe LED and the light receiving device but also to obtain in advance theposition at which the liquid Lq is held to select the LED and the lightreceiving device to be driven according to the position. By thusconfiguring, it becomes possible to control the photometric position.

The automatic analyzer 60 analyzes the liquid held in the reactionvessel 7 in the manner similar to the photometric method of theautomatic analyzer 1 including the process to control the photometricposition for performing the photometry of the liquid according to theholding position at which the liquid is held in the reaction vessel 7,and the process to perform the photometry of the liquid at thecontrolled photometric position.

At this time, as shown in FIG. 49, when the dispensing amount of theliquid Lq is small, since the capacity of the reaction vessel 7 is asextremely small as a few nanoliters (nL) to several tens of microliters(μL), the liquid Lq is held in the vicinity of the opening 7 e due tothe large effect of the surface tension. Therefore, the control unit 16obtains the amount of the liquid Lq from the dispensing amounts of thespecimen and the reagent input from the specimen dispensing mechanism 5and the reagent dispensing mechanism 12, respectively, and sequentiallyswitches the LED 62 a and the light receiving device 63 a based on thetable and the function for deciding the photometric position obtained inadvance based on the obtained amount of the liquid Lq, therebyperforming the photometry of the liquid Lq in the vicinity of theopening 7 e while controlling the photometric position.

However, the position at which the reaction vessel 7 holds the liquid Lqincluding the reagent and the specimen varies according to at least oneof the kind or the amount of the liquid Lq and the form or the materialof the reaction vessel 7. Therefore, for example, there might occur acase in which the dispensing amounts of the reagent and the specimen arelarge and the amount of the liquid Lq is large, so that the liquid Lqintrudes halfway into the liquid holding section 7 d from the vicinityof the opening 7 e, or a case in which the liquid Lq of which amount issmall intrudes halfway into the liquid holding section 7 d from thevicinity of the opening 7 e.

In this case, the control unit 16 may perform the photometry of theliquid Lq in the vicinity of the opening 7 e, which is the initialposition of the photometry unit 10 without controlling the photometricposition, or may perform the photometry of the liquid Lq whilecontrolling the photometric position by sequentially switching the LED62 a and the light receiving device 63 a. Also, in a case in which theliquid Lq of which amount is small intrudes into the liquid holdingsection 7 d, it is understood that the liquid does not exist in thevicinity of the opening 7 e from the photometric data in the vicinity ofthe opening 7 e. Therefore, in the automatic analyzer 60, the controlunit 16 performs the photometry of the liquid Lq in the vicinity of theopening 7 e while controlling the photometric position by sequentiallyswitching the LED 62 a and the light receiving device 63 a located inthe range decided based on the table and the function, from the positionat which the presence of the liquid is detected and the information ofthe dispensing amount.

In this manner, in the automatic analyzer 60 of the sixth embodiment,since the control unit 16 sequentially switches the LED 62 a and thelight receiving device 63 a according to the position of the liquid heldin the reaction vessel 7, the photometric position may be controlled inaccordance with the position of the liquid held in the reaction vessel7, and this allows for the photometry of the liquid held in the reactionvessel 7 even though the liquid is not introduced to the bottom portionof the reaction vessel as in the conventional analyzer.

Especially, in the automatic analyzer 60 of the sixth embodiment, sincethe position detector of the present invention is formed of thephotometry unit 61 and the control unit 16, which becomes the detectingsection for detecting the position of the liquid held in the reactionvessel 7, the position of the liquid held in the reaction vessel 7 isdetected, and the control unit 16 sequentially switches the LED 32 a andthe light receiving device 33 a according to the detected position ofthe liquid, it is possible to perform the photometry of the liquid bythe photometry unit 31 at the position of the liquid held in thereaction vessel 7. In this manner, the position detector described inthe sixth embodiment may detect the position of the liquid held in thereaction vessel 7 with a simple configuration, and the automaticanalyzer 60 may perform the photometry of the liquid at the position ofthe liquid held in the reaction vessel 7. Also, as in the firstembodiment, since the position of the liquid may be detected fromoutside the reaction vessel 7 without contacting the liquid in thereaction vessel 7, the position detector described in the sixthembodiment may prevent another substance from being mixed into thereaction vessel 7 when used in the automatic analyzer 60.

Also, the automatic analyzer 60 does not use the driver for drivingmovable parts such as the movable mirrors 56 b and 57 b as in theautomatic analyzer 55 of the fifth embodiment, so that it is possible tocut the process of reducing the noise received by the light source 66and the light receiving device array 63 and the reference photometry.

Herein, as one modification of the fifth embodiment, the automaticanalyzer 60 may have a single light source 66 in place of the lightsource array 62 as shown in FIG. 50, and switch the control signaloutput from the control unit 16 by the switch circuit 65. Then, thephotometry of the liquid Lq is performed in the vicinity of the opening7 e of the reaction vessel 7 by sequentially receiving the analyticallight emitted from the light source 66 by a plurality of light receivingdevices 63 a. Thereby, the control unit 16 may detect the holdingposition of the liquid from the photometric data output from each of thelight receiving devices 63 a together with the photometry. Herein, thecontrol unit 16 selects the light receiving device 63 a existing at theposition based on the dispensing amounts of the specimen and the reagentinput from the specimen dispensing mechanism 5 and the reagentdispensing mechanism 12, respectively, when selecting a specific lightreceiving device 63 a to be used in the photometry. Accordingly, theautomatic analyzer 60 may perform the photometry of the liquid Lq whilecontrolling the photometric position by the light receiving device array63 in accordance with the position of the liquid Lq held in the reactionvessel 7 by selecting the specific light receiving device 63 a by thecontrol unit 16 even when the amount of the liquid held in the reactionvessel 7 is large. Meanwhile, the single light source is provided on anemitting surface of the light source such that a lens for parallelizingmeasurement light corresponds to each component of a facing lightreceiving device.

On the other hand, as another modification of the fifth embodiment, theautomatic analyzer 60 may sequentially light a plurality of LEDs 62 a ofthe light source array 62 by using a single light receiving device 67 inplace of the light receiving device array 63 and by switching thecontrol signal output from the control unit 16 by the switch circuit 64as shown in FIG. 51. In addition, it is possible to perform thephotometry of the liquid Lq in the vicinity of the opening 7 e of thereaction vessel 7 by sequentially receiving the analytical light emittedfrom each LED 62 a by the light receiving device 67. Thereby, thecontrol unit 16 may detect the holding position of the liquid byspecifying the LED 62 a, which has emitted the analytical light havingpenetrated the liquid Lq from a plurality of photometric data outputfrom the light receiving device 67. Herein, the control unit 16 selectsthe LED 62 a existing at the position based on the dispensing amounts ofthe specimen and the reagent input from the specimen dispensingmechanism 5 and the reagent dispensing mechanism 12, respectively, whenselecting the LED 62 a to be lit. Accordingly, the automatic analyzer 60may perform the photometry of the liquid Lq while controlling thephotometric position by the light source array 62 in accordance with theposition of the liquid Lq held in the reaction vessel 7, by selectingthe LED 62 a to be lit by the control unit 16 even when the amount ofthe liquid held in the reaction vessel 7 is large.

As is clear from the above description, according to the modifiedexamples 1 and 2, it is possible to reduce the number of components ofthe light source, the light receiving section and the switch circuit.

Additional advantages and modifications will readily occur to thoseskilled in the art. Therefore, the invention in its broader aspects isnot limited to the specific details and representative embodiments shownand described herein. Accordingly, various modifications may be madewithout departing from the spirit or scope of the general inventiveconcept as defined by the appended claims and their equivalents.

1-20. (canceled)
 21. An analyzer for measuring optical characteristicsof liquid, comprising: a vessel for holding the liquid in a state ofhaving at least two gas-liquid interfaces; and a photometric unit thatmeasures the optical characteristics of the liquid held in the vessel.22. The analyzer according to claim 21, wherein in the vessel, a sum ofa vertical component of surface tension acting from the liquid on anentire circumference of an inner wall of the vessel and force actingvertically upward from gas in the vessel on the liquid is not less thanweight of the liquid, when the at least two gas-liquid interfaces arearranged up and down in the vertical direction.
 23. The analyzeraccording to claim 21, wherein the photometric unit measures the opticalcharacteristics of the liquid in a portion enclosed by the vesselbetween the at least two gas-liquid interfaces.
 24. The analyzeraccording to claim 21, wherein the photometric unit measures the opticalcharacteristics of the liquid along a direction orthogonal to a movingdirection of the liquid held in the vessel.
 25. The analyzer accordingto claim 21, further comprising: a dispensing unit that dispenses theliquid to the vessel; and a stirring unit that stirs dispensed liquid,wherein another liquid is dispensed and stirred and the opticalcharacteristics thereof are measured at a position at which the liquidis held in the vessel.
 26. The analyzer according to claim 21, whereinthe photometric unit measures the optical characteristics of the liquidin a case in which at least one gas-liquid interface exists outside thevessel.
 27. The analyzer according to claim 21, wherein the photometricunit measures the optical characteristics of the liquid in a case inwhich all of the gas-liquid interfaces, which the liquid has, exist inthe vessel.
 28. The analyzer according to claim 21, further comprising acontrol unit that controls a photometric position when measuring theoptical characteristics of the liquid.
 29. The analyzer according toclaim 28, wherein the control unit controls the photometric positionaccording to at least one of a kind or an amount of the liquid and aform or a material of the vessel.
 30. A vessel used in an analyzer formeasuring optical characteristics of liquid, comprising: an opening forintroducing the liquid; and a liquid holding section for holding theliquid introduced from the opening in a state of having at least twogas-liquid interfaces.
 31. The vessel according to claim 30, wherein inthe vessel, a sum of a vertical component of surface tension acting fromthe liquid on an entire circumference of an inner wall of the vessel andforce acting vertically upward from gas in the vessel on the liquid isnot less than weight of the liquid in a case in which the at least twogas-liquid interfaces are arranged up and down in the verticaldirection. 32-45. (canceled)